The present invention relates, in general, to a means for measuring relative humidity and, more particularly, the present invention relates to a battery powered humidity indicator.
Air dryers are used routinely in the railroad industry to provide clean, dry compressed air to locomotive and train air systems. Not only are air dryers used within the railroad industry but they are also widely used throughout other parts of general industry for similar purposes as with the railroad industry, that is, to provide dry, clean air. Some examples of air drying systems are found in U.S. Pat. No. 5,961,698 and U.S. Pat. No. 5,715,621. These patents are assigned to the Assignee of the present invention and their teachings are incorporated into the present document by reference thereto. In order to be certain that an air dryer is functioning properly it is necessary to measure the relative humidity of both the atmospheric air that enters the air dryer and the air exiting the air dryer that supplies such compressed air systems.
Generally, humidity measurements have been made in many of the commercial air drying systems by the use of a dyed paper which determines the an increase in humidity by a change in the paper color. Such a system, although functional, leaves a lot to be desired. One major problem with such dyed paper systems is that the paper is not regenerative in that it loses its ability to change color after a period of time. This is particularly true if the paper is exposed to very high humid air, in which case the dye in the paper may be essentially washed out and thus the paper can no longer give an indication of humidity.
Another drawback to the present system is that the paper is very slow to respond which can create problems. This is particularly true with today""s rapid pace in virtually everything where results are expected instantly. Such slow response time is compounded by the fact that the dyed paper system is also relatively inaccurate. Generally, the accuracy of the dyed paper system is in the order of xc2x125 percent.
Thus, it would appear advantageous not only for use in air drying systems but for any measurement of relative humidity if a rapid, accurate, regenerative system were developed.
The present invention provides an apparatus that is used to measure relative humidity, such apparatus comprises a housing having a first end and a second end. There is a humidity sensor disposed at the first end of the housing for measuring the humidity in the air and a temperature sensor also disposed at the first end of the housing for measuring ambient temperature. The apparatus has an electronics portion in direct electrical communication with the humidity sensor and the temperature sensor for computing a relative humidity and a dewpoint temperature. The electronics portion is disposed within a center portion of the housing. There is, further, a battery that is in electrical communication with the electronics portion, the humidity sensor and the temperature sensor for providing power to the apparatus. Such battery is disposed in the center portion of the housing of the apparatus. The apparatus has a display means that is in electrical communication with the electronics portion and with the battery for displaying such relative humidity and such dew point temperature as determined by the electronics portion. The display means is disposed at a second end of said housing.
In an alternate embodiment of the invention there is provided in combination with an air drying system having a first housing member, an air inlet manifold and an air outlet manifold disposed in the first housing member, a pair of towers disposed in the first housing, a first one of a pair of towers serving as a drying tower fluidly connected to the air inlet manifold and the air outlet manifold whenever a second one of the pair of towers is being regenerated and the second one of the pair of towers serving as a drying tower when the first one of the pair of towers is being regenerated, the improvement comprises at least one apparatus disposed in the housing for measuring humidity. The at least one apparatus is fluidly connected to the air inlet manifold, the air outlet manifold and the at least one of the pair of towers, the at least one apparatus includes a second housing member and a humidity sensor that is disposed at a first end of the second housing member for measuring humidity in ambient air. A temperature sensor is disposed at the first end of the second housing member for measuring ambient temperature.
An electronics portion is disposed in the second housing member and is electrically connected to the humidity sensor and the temperature sensor for computing at least one of a relative humidity and a dewpoint temperature.
A power means is electrically connected to the electronics portion, the humidity sensor and the temperature sensor for providing power to the apparatus, and a display means is electrically connected to the electronics portion and the power means for displaying at least one of such relative humidity and such dewpoint temperature as determined by said electronics portion. The display means is disposed at a second end of the second housing member.
It is, therefore, one of the primary objects of the present invention to provide a humidity indicator that is regenerative.
Another object of the present invention is to provide a humidity indicator that responds rapidly.
Still another object of the present invention is to provide a humidity indicator that is accurate.
Yet another object of the present invention is to provide a humidity indicator that can be used with air drying equipment.
An additional object of the present invention is to provide a humidity indicator that can provide a digital readout.
Also it is an object of the present invention to provide a humidity indicator that can provide a warning that the battery needs replacement.
In addition to the numerous objects and advantages of the present invention which have been described with some degree of particularity above, it should be both noted and understood that a number of other important objects and advantages of the battery powered humidity indicator will become more readily apparent to those persons who are skilled in the relevant art from the following more detailed description of the invention, particularly, when such detailed description is taken in conjunction with the attached drawing Figures and with the appended claims.